Link layer assisted robust header compression context update management

ABSTRACT

A method and system for communicating header compression layer control messages. Header compression control messages are generated by a header compression layer and are sent through at least one link layer data packet by a link transport communications protocol layer to a remote receiver. The link transport communications protocol layer monitors receipt of link layer data packet acknowledgements that are received from the link transport communications protocol layer of the remote receiver for the at least one link layer data packet. The link transport communications protocol layer determines successful transmission of the header compression control message and provides, to the header compression layer, an indication of successful header compression control message transmission.

CROSS-REFERENCE TO RELATED APPLICATION

Not Applicable

FIELD OF THE INVENTION

The present invention generally relates to the field of datacommunications, and more particularly relates to packet datacommunications protocols using packet header compression.

BACKGROUND OF THE INVENTION

Data communications systems that utilize both wired and wireless datacommunications standards often transmit data in packetized messages.These packetized messages often include a header portion to containcommunications protocol related information. Some protocols incorporateheader compression (HC) processing to reduce bandwidth utilization,which is particularly useful with wireless links. For example, astandard implementing a Robust Header Compression (RoHC) protocol isdesigned to efficiency minimize the size of RTP, UDP and IP headers bycompressing dynamic fields of these headers using a window basedencoding mechanism. In a wireless access network, RoHC can be used tocompress various higher layer protocol headers over the radio link. Toenable compression of various protocol headers over the radio link, RoHCis implemented on subscriber equipment (e.g. mobile, CPE, etc) and on anode in an access network. Equipment options for implementing the RoHCprocessing in access network can either be in the base station or in anexternal, off-the-shelf, radio access router such as PDSN (Packet DataServing Node), GGSN (Gatway GPRS Support Node), RNC (Radio NetworkController), ASN-GW (ASN Gateway), and the like. RoHC requires thecompressor and the de-compressor to establish and maintain contextinformation that is used for compression and de-compression purposes.The compressor and the de-compressor are required to maintainsynchronized context to ensure that the de-compressor is able tocorrectly de-compress the packets compressed by the compressor. Sincethe context information is crucial for operation of the RoHC protocol,it is essential to use a reliable context update mechanism betweencompressor and de-compressor.

The RoHC RFC (3095) defines in-band signaling from de-compressor tocompressor to enable efficient encoding as well as quick recovery fromover the air packet loss and radio link frame corruption containingcompressed headers. The in-band signaling is used by the de-compressorto acknowledge the context update signaling received from thecompressor. The explicit acknowledgement signaling mechanism makes theheader compression protocol self contained and independent of theunderlying link layer but it also introduces additional radio linkoverhead making it less spectral efficient.

The RoHC protocol uses W-LSB encoding to compress various changing filedof RTP/UDP/IP headers. The W-LSB encoding requires compressor tomaintain window of reference points that it uses to compress variouschanging fields of RTP/UDP/IP header. Depending upon the mode ofoperation, window size is either manually configured or adjusted basedupon explicit feedback from the de-compressor to the compressor. Theaccuracy of W-LSB de-compression depends upon the reference points beingused by compressor being synchronized with those used by thede-compressor for de-compression purpose. In the Robust (R)-mode ofoperation, the RoHC compressor adjusts its window size as soon as itreceives feedback from the de-compressor that a particular contextupdate packet containing a given reference point is received by thede-compressor. In case of either U or O mode, the RoHC compressormanually configures the window size and sends the reference updateseveral times to ensure that de-compressor receives the reference pointsbefore it discards the reference point from its compressor window.

Although both of these approaches perform their required functionality,they consume communications bandwidth by requiring transmission of theseadditional synchronization messages. For example, In the R mode ofoperation, additional messages are sent from the de-compressor to thecompressor to update the window size. In case of U or O modes, the W-LSBwindow size is chosen in such a way that compressor and de-compressor donot get into situation where their reference points are out of sync.This selection of a larger window size reduces the bandwidth efficiencyof W-LSB encoding and thereby reduces some of the spectral efficiencygain that is obtained from using the Robust Header Compression protocol.

Therefore a need exists to overcome the problems with the prior art asdiscussed above.

SUMMARY OF THE INVENTION

Briefly, in accordance with one aspect of the present invention a methodfor communicating header compression layer control messages includessending, by a link transport communications protocol layer to a remotereceiver, at least one link layer data packet conveying a headercompression control message received from a header compression layer.The method also includes monitoring, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements received from the link transport communicationsprotocol layer of the remote receiver for the at least one link layerdata packet. The method also includes determining, at the link transportcommunications protocol layer, successful transmission of the headercompression control message. The method also includes providing, to theheader compression layer, an indication of successful header compressioncontrol message transmission.

In accordance with another aspect of the present invention, a headercompression layer control message communications system includes a linktransport communications protocol transmitter adapted to send to aremote receiver, according to a link transport communications protocollayer, at least one link layer data packet conveying a headercompression control message received from a header compression layer.The header compression layer control message communications systemfurther includes a link transport communications protocolacknowledgement receiver adapted to monitor, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements received from a link transport communications protocollayer of the remote receiver for the at least one link layer datapacket. The header compression layer control message communicationssystem also includes a header compression control message transmissionmonitor adapted to determine, at the link transport communicationsprotocol layer, successful transmission of the header compressioncontrol message. The header compression layer control messagecommunications system also includes a link transport communicationsprotocol to header compression layer interface adapted to provide, tothe header compression layer, an indication of successful headercompression control message transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures where like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages allin accordance with the present invention.

FIG. 1 illustrates a block diagram of a two transceiver communicationssystem in accordance with an embodiment of the present invention.

FIG. 2 illustrates a transceiver protocol stack as is utilized by anembodiment of the present invention.

FIG. 3 illustrates a compressed header data message communications flowin accordance with one embodiment of the present invention.

FIG. 4 illustrates a header compression transmission processing flow inaccordance with one embodiment of the present invention.

FIG. 5 illustrates a header compression state message transmissionprocessing flow in accordance with one embodiment of the presentinvention.

FIG. 6 illustrates a block diagram of a communications processor as isincluded in the transceiver A and transceiver of FIG. 1, in accordancewith one embodiment of the present invention.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely examples of the invention, which can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as illustrativeexamples for the claims and as a representative basis for teaching oneskilled in the art to variously employ the present invention invirtually any appropriately detailed structure. Further, the terms andphrases used herein are not intended to be limiting; but rather, toprovide an understandable description of embodiments of the invention.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms including and/or having, as used herein, are definedas comprising (i.e., open language). The term coupled, as used herein,is defined as connected, although not necessarily directly, and notnecessarily mechanically.

One embodiment of the present invention operates to improve spectralefficiency of data communications by using Media Access Control layertriggers to optimize header compression processing and obviating therequirement for the header compression processing to explicitly sendacknowledgments for control messages used to coordinate headercompression and de-compression processing. One embodiment utilizesconventional window-based least significant bit (W-LSB) data compressiontechniques to compress fields within message headers. The headercompression control messages utilized by one embodiment of the presentinvention include, for example, header compression context messages,Robust Header Compression Protocol IR (Initialization and Refresh)messages, Robust Header Compression Protocol IR-DYN (Initialization andRefresh dynamic) messages, and Robust Header Compression Protocol PacketType 2 messages (e.g., UOR-2, UOR-2-ID, UOR-2-TS) and any other contextupdate messages.

The header compression components within the protocol stacks of oneembodiment are adapted to interface with a modified ARQ or H-ARQ linklayer to perform efficient transmission of header compression controlmessages. Header compression control messages coordinate and synchronizethe operation of the header compression and decompression processing,such as context update. The ARQ/H-ARQ link layer keeps track of whichlink layer data packets correspond to header compressor control messagesand monitors which packets are acknowledged by the receivingtransceiver. When all of the link layer data packets that correspond tothe header compression control message have been received by theARQ/H-ARQ link layer, the ARQ/H-ARQ link layer sends a message to theheader compression layer indicating successful transmission of thatheader compression control message. Failure to receive anacknowledgement for any one packet results in a message indication of afailed transmission, which is a negative indication of a successfultransmission.

In an example, The Robust header Compression (RoHC) standard RFC3095defines different levels of robustness where header compression controlmessages are either acknowledged by a remote header compression layerthat receives the control message, or requires several retransmissionsof control messages that are not explicitly acknowledged by thereceiver. One embodiment of the present invention obviates therequirement for either the explicit header compression layeracknowledgements or retransmissions by providing a verification ofreceipt for header compression control messages based upon monitoringlink layer acknowledgements. A failure of the header compression controlmessage transmission is determined by a failure to receive positiveacknowledgement for any one link layer data packet communicating theheader compression control message, or by information received in a NACKmessage for those link layer data packets.

FIG. 1 illustrates a block diagram of a two transceiver communicationssystem 100 in accordance with an embodiment of the present invention.The two transceiver communications system 100 includes a transceiver A102 and a transceiver B 104 that wirelessly communicate data over awireless link 108. Transceiver A 102 and Transceiver B 104 each have atransmitter and a receiver that is used to perform wirelesscommunications with each other or with other receivers, transmitters ortransceivers. Each of the transceiver A 102 and transceiver B 104 acceptdata from and provide data to a respective data source and processor106. The data source and processor 106 of various embodiments are ableto include any type of data application, such as a computercommunicating data, a bi-directional digital voice telephony system, orany other type of application and/or device that is capable of producingand/or accepting data. Further embodiments operate with data source andprocessors 106 that either only produce data for transmission overwireless link 108 or only accept data received by a transceiver over thewireless link 108.

Transceiver A 102 and transceiver B 104 of various embodiments are ableto communicate over any suitable wireless transmission protocol, such asprotocols defined under IEEE 802.16, various digital cellular voice anddata networks, and the like. Further embodiments are able to operateover wired networks or any other suitable communications medium able tocommunicate digital data. As is known to ordinary practitioners in therelevant arts in light of the present discussion, transceivers, such asTransceiver A 102 and Transceiver B 104, include data communicationsprocessing that divides communications processing into layers of one ormore communications stacks. The processing of such transceivers acceptsuser data at a highest layer of the communications stack, and thesubordinate layers of the communications stack perform variousprocessing to communicate that data to a remote transceiver. Each layerof the communications stack formats the data according to therequirements of that layer. Each layer is also able to communicatecontrol messages to the corresponding communications protocol layer inthe remote transceiver.

FIG. 2 illustrates a transceiver protocol stack 200 as is utilized by anembodiment of the present invention. The transceiver protocol stack 200has a physical layer (PHY) 202 that couples to a physical communicationsmedium and performs the processing required to transmit data over awireless link 108 from a transmitter in a transceiver to a remotereceiver within a remote transceiver. The physical layer 202 acceptsdata for transmission and provides received data to a privacy sublayer204. The privacy sublayer 204 encrypts/de-crypts packet payload data toprovide secure data transmission.

The privacy sublayer 204 in turn accepts data for transmission andprovides received data to a Media Access Controller (MAC) common partssublayer 206. The MAC common parts sublayer 206 provides various MAClevel processing to implement the required communications protocols. TheMAC common parts sublayer 206 of one embodiment includes an AutomaticRepeat Request (ARQ) link layer for the communications protocol beingutilized for wireless data communications. Further embodiments of thepresent invention utilize Hybrid-ARQ, or H-ARQ, protocols and haveassociated processing in the MAC common parts sublayer 206 to performthe processing required by the H-ARQ protocol. ARQ and H-ARQcommunications protocols are known to ordinary practitioners in therelevant arts and operate to communicate link layer data packets over acommunications link. Once a receiver receives one or a pre-definednumber of data packets, some embodiments transmit an “acknowledgement,”or “ACK” packet, from the receiver to the transmitter to indicatereceipt of those packets. Some embodiments further support transmissionof “Negative Acknowledgement,” or “NACK” packets from the receiver tothe transmitter to indicate packets that were not properly received. Inresponse to either not receiving an expected ACK packet or receiving aNACK packet, the link layer data packets that were transmitted but notindicated as successfully received are generally retransmitted until amaximum retransmission count is reached. If the transmitted link layerdata packets have not be indicated as received, the transmission ofthose link data packets is then determined to be unsuccessful and thelink layer data packet receipts have been failed to be verified.

The MAC common parts sublayer 206 accepts data for transmission andprovides received data to a Service Specific Convergence Sublayer (CS)208. The CS sublayer includes processing to implement, for example, PHSfunctionality. The CS sublayer 208 accepts data for transmission andprovides received data to “Robust Header Compression” (RoHC) sublayer209 that performs data compression and decompression processing forcertain fields of the headers of data messages transmitted over awireless link 108. The operation of the RoHC layer 209 of oneembodiment, and it interaction with the ARQ link transport layer of theMAC Common Parts Sublayer 206, is described in further detail below. TheRoHC protocol of one embodiment of the present invention utilizes aWindow-based Least Significant Bit (W-LSB) compression algorithm tocompress some changing fields in message headers to be communicated tothe remote transceiver. The W-LSB compression algorithm is known toordinary practitioners in the relevant arts.

The RoHC sublayer 209 of one embodiment of the present invention acceptsdata for transmission from and provides received data to an IP transportlayer 212. Further embodiments of the present invention are further ableto include an Ethernet convergence sublayer (not shown). The IPtransport layer 212 in one embodiment of the present invention exchangedata with the RoHC sublayer 209 in a conventional manner. Furtherembodiments of the present invention exchange data from the RoHCsublayer 209 with other communications processes or entities.

FIG. 3 illustrates a compressed header data message communications flow300 in accordance with one embodiment of the present invention. Thecompressed header data message communications flow 300 illustratescommunications of data messages with compressed headers from a headercompression layer 302 in a transmitting transceiver, such as transceiverA 102, to a header de-compression layer 306 in a receiving transceiver,such as transceiver B 104. The compressed header data messages of thisembodiment have some data fields within the message headers compressedby a Window-based Least Significant Bit (W-LSB) compression algorithm.In addition to transmitting data messages with compressed headersbetween the header compression layer 302 and the header de-compressionlayer 306, one embodiment of the present invention further communicatesheader compression control messages from the header compression layer302 to the header de-compression layer 306 in order to support propercompressed header de-compression. One embodiment of the presentinvention performs header compression processing, including compressionof header information using W-LSB compression algorithms and generationof header compression control messages, in a conventional manner whilemodifying the communication of receipt acknowledgement processing forsome or all of those messages as described below.

The compressed header data message communications flow 300 illustrates aheader compression layer 302 that accepts data from a higher levellayers 310. The header compression layer 302 forms a data message fortransmission to a remote receiver that includes a compressed messageheader. The header compression layer 302 of one embodiment sends a datamessage 320 with a compressed header through the intervening layersdescribed above for the transceiver protocol stack 200 to the ARQ linktransport layer 304.

In order to support synchronization of compressor and de-compressorcontext information, the header compression layer 302 generates headercompression control messages 322 with appropriate context informationthat are to be sent to the header de-compression layer 306. The headercompression control messages 322 are first provided to the ARQ linktransport layer 304 of the sending transceiver for transmission to thereceiving transceiver over the physical communications layer, whichcouples to the physical communications medium of a wireless link 308,through the ARQ link transport communications protocol stack.

The ARQ link transport layer 304 of the exemplary embodiment performsconventional ARQ link communications processing to send data from theARQ link transport layer 304 of one transceiver to the ARQ linktransport layer 304 of a remote transceiver. As is known by ordinarypractitioners in the relevant arts, ARQ link transport layer 304 is ableto accept a data message from the header compression layer 302 anddivide that accepted message into multiple link layer data packets fortransmission over the physical layer 202, including over the wirelesslink 308. A receiving ARQ link transport layer 304 will send anacknowledgement message indicating which link layer data packets havebeen successfully received.

In order to support proper processing by the ARQ link transport layer304, the header compression layer 302 precedes each header compressioncontrol message or data message with compressed header with anotification message containing information about the message to beprovided to ARQ link transport layer 304. This notification allows thesending ARQ link transport layer 304 to identify which transmitted linklayer data packets correspond to a particular header compression controlmessage or data message with compressed header. The sending ARQ linktransport layer 304 is then able to correlate link layer data packetstransmitted over the physical layer, including the wireless link 308, toa respective message received from the header compression layer 302. TheARQ link transport layer 304 is then able to correctly monitor theacknowledgements or negative acknowledgements sent through the physicalcommunications layer for those transmitted link layer data packets. Thisto verify receipt of link layer data packet receipt acknowledgementsfrom the remote receiver for each link layer data packet transmitted,thereby determining if the entire header compression control message ordata message with compressed header has been properly received. If theentire transmission has been successfully received, the transmitting ARQlink transport layer 304 provides a positive indication of successfulmessage transmission to the header compression layer 302 that serves asan acknowledgement of the receipt of the message sent by the headercompression layer 302. If not all of the link layer data packetstransmitted by the ARQ link transport layer 304 for a particular headercompression control message or data message with compressed header arenot properly acknowledged by the receiving ARQ link transport layer, thetransmitting ARQ link transport layer 304 fails to verify receipt oflink layer data packet receipt acknowledgements for all link layer datapackets and therefore provides a negative indication of successfulmessage transmission to the header compression layer 302. Link layerdata packets received by the receiving ARQ link transport layer 304 areprovided to a header de-compression layer 306, which performs thedecompression processing for the header, and then produces the data tohigher level layers 312. Header compression control messages are alsoprovided to the header de-compression layer 306 and processed to controlthe internal operation of the header de-compression layer 306.

FIG. 4 illustrates a header compression transmission processing flow 400in accordance with one embodiment of the present invention. The headercompression transmission processing flow 400 begins by establishing, atstep 402, a connection between a transmitter, such as transceiver A 102,and a remote receiver, such as transceiver B 104. The processing thenproceeds to establishing, at step 404, a header compression protocolover the established connection.

Once a header compression protocol is established between thetransmitter and the remote receiver, the processing proceeds togenerating, at step 406, a header compression context message at thetransmitter for transmission to the remote receiver. The contents ofthis header compression context message in one embodiment of the presentinvention comply with a definition of a header compression contextmessage defined for a conventional header compression protocol. Theprocessing proceeds by providing, at step 408, a header compressioncontext message notification along with the header compression contextmessage to a communications protocol ARQ link transport layer. Theheader compression context message notification that is provided to theARQ link transport layer 304 specifies, for example, a PID, messagetype, payload, and the like. The header compression context messagenotification allows the ARQ link transport layer processing to trackwhich link layer data packets sent by the ARQ link transport layer arepart of the header compression context message

After the ARQ link transport layer has received the header compressioncontext message, the processing advances to sending, at step 410, theheader compression context message through the ARQ link transport layerover a wireless link to the remote receiver. The ARQ link transportlayer 304 generally divides the header compression context message intoa number of link layer data packets for transmission over the wirelesslink.

The processing then proceeds to monitoring and receiving, at step 412,ARQ transport link layer ACK/NACK messages from a remote receiver's ARQlink transport layer 304. These ACK/NACK messages are sent to indicatethe receipt of each transmitted link layer data packet. The processingof the ARQ transport link layer 304 of one embodiment of the presentinvention tracks the receipt status for each link layer data packetassociated with each header compression context message based upon ACKand/or NACK messages received from a remote receiver's ARQ linktransport layer.

After all of the ARQ link layer data packets have been successfullyreceived or the ARQ link transport layer processing determines that thetransmission of any ARQ link transport layer packet has failed, theprocessing provides, at step 414, an indication of successful headercompression context message communications to the header compressionlayer 302. This indication is able to be positive or negative. Theprocessing next determines, at step 416, if the transmission wassuccessful. If the transmission was not successful, the processingretransmits the header compression context message by returning to theheader compression layer's 302 generating, at step 406, the headercompression context message. A particular header compressioncommunications protocol implemented by various embodiments of thepresent invention is able to adjust or delay the generation, andsubsequent retransmission, of the header compression context messageaccording to that protocol's requirements. If the transmission wassuccessful, as determined at step 416, the processing awaits, at step418, a context change within the ARQ link transport layer. After acontext changes within the ARQ link transport layer, the processingreturns to generating, at step 406, a header compression context messagefor transmission to the remote receiver, as described above.

FIG. 5 illustrates a header compression state message transmissionprocessing flow 500 in accordance with one embodiment of the presentinvention. The header compression state message processing flow 500begins by changing, at step 501, a header compression processor statewithin the header compression layer 302. The processing continues bycreating, at step 502, a header compression state message within aheader compression layer, such as within the header compression layer302. The processing then continues by providing, at step 504, a headercompression state message notification and the header compression statemessage to a communications protocol ARQ link transport layer 304.

In a manner similar to that discussed above with regards to thecompressed header context message, The ARQ link transport layer 304 isable to divide header compression state messages into multiple ARQ linklayer data packets for transmission over the wireless link 308. In orderto support determining successful transmission of the header compressionstate message, the ARQ link transport layer 304 accepts a headercompression state message notification that specifies, in one example, aPID, message type, payload, and the like. The header compression statemessage notification allows the ARQ link transport layer 304 tocorrelate the ARQ link layer data packets with a particular headercompression state message.

The processing then continues by sending, at step 506, the headercompression state message through the communications protocol ARQ linktransport layer over a wireless link to the remote receiver. Asdescribed above, this transmission is able to involve multiple ARQ linklayer data packets for each header compression state message. The ARQlink transport layer 304 of one embodiment of the present inventionmonitors, at step 508, ARQ link transport layer ACK/NACK messagereception from the remote receiver to determine the transmission successfor the transmitted header compression state message. The processingthen provides, at step 510, an indication, which is either positive ornegative, to the header compression layer 302 of the successful headercompression state message transmission.

The processing next determines, at step 512, if the transmission wassuccessful. If the transmission was successful, the processing continuesby awaiting, at step 516, a change of state of the header compressionprocessor. Once a state changes within the header compression processor,the processing returns to creating, at step 502, a header compressionstate message that reflects this changed state. If the transmission wasnot successful, the processing configures for retransmission, at step514, of the header compression state message transmission. Theprocessing then returns to sending, at step 506, the header compressionstate message through the communications protocol ARQ link layer over awireless link to the remote receiver.

FIG. 6 illustrates a block diagram of a communications processor 600 asis included in the transceiver A 102 and transceiver B 104 of FIG. 1, inaccordance with one embodiment of the present invention. Thecommunications processor 600 in this example performs the communicationsrelated processing of these transceivers. In addition to the headercompression control message processing described below, thecommunications processor 600 of one embodiment of the present inventionfurther performs the other communications processing as required by thevarious protocols implemented by the transceiver.

The programmable signal processor 600 includes a CPU 602 that performsthe programmed processing defined by processing programs, as isdescribed below. The CPU 602 of some embodiments of the presentinvention are able to include programmable microprocessors,pre-configured reconfigurable gate arrays, and/or any other suitablesignal processing hardware capable of being configured or re-configuredto perform pre-programmed or re-programmable tasks. The CPU 602 acceptsdata to be transmitted and provides received data through a datainterface 604. Data Interface 604 provides an interface in oneembodiment to a data source and processor 106. The CPU 602 provides datato and accepts data from a physical channel interface 606. The physicalchannel interface exchanges data with physical channel equipment which,for example, transmits and/or receives data through a wired or wirelessphysical communications channel to a remote receiver, transmitter, ortransceiver.

The CPU 602 further accepts a computer program product that is encodedon a physical media that is ready by program reader 608. Program reader608 reads a computer readable medium to extract a computer program, andprovides that computer program to CPU 602 to be encoded into programmemory 612, described in more detail below.

The communications processor 600 includes a program memory 612 thatstores programs that define the processing defined for the CPU 602. Theprogram memory 612 of one embodiment of the present invention includes alink transport communications protocol transmitter program 620 that isadapted to send to a remote receiver, according to a link transportcommunications protocol layer, at least one link layer data packetconveying a header compression control message received from a headercompression layer. The link transport communications protocoltransmitter is also adapted to send to the remote receiver, according toa link transport communications protocol layer, a second at least onelink layer data packet conveying to the second header compressioncontrol message. The link transport communications protocol transmitteris further adapted to divide the header compression control message intoa plurality of link layer data packets, and associate each link layerdata packet within the plurality of link layer data packets with theheader compression control message.

The program memory 612 further includes a link transport communicationsprotocol acknowledgement receiver program 622 that is adapted tomonitor, at the link transport communications protocol layer, link layerdata packet receipt acknowledgements received from a link transportcommunications protocol layer of the remote receiver for the at leastone link layer data packet. The link transport communications protocolacknowledgement receiver is also adapted to monitor by verifying receiptof link layer data packet receipt acknowledgements from the remotereceiver for each link layer data packet within the plurality of linklayer data packets.

The program memory 612 further includes a header compression controlmessage transmission monitor program 624 that is adapted to determine,at the link transport communications protocol layer, successfultransmission of the header compression control message. The headercompression control message transmission monitor is further adapted tomonitor, at the link transport communications protocol layer, link layerdata packet receipt acknowledgements received from the link transportcommunications protocol layer of the remote receiver for the second atleast one link layer data packet.

The program memory 612 further includes a link transport communicationsprotocol to header compression layer interface program 626 that isadapted to provide, to the header compression layer, an indication ofsuccessful header compression control message transmission. The linktransport communications protocol to header compression layer interfaceis further adapted to provide, to the header compression layer, anindication of successful second header compression control messagetransmission. The link transport communications protocol to headercompression layer interface is additionally adapted to provide, from thelink transport communications protocol layer in response to verifyingreceipt of link layer data packet receipt acknowledgements for all linklayer data packets within the plurality of link layer data packets, apositive indication of successful header compression control messagetransmission, and to provide, from the link transport communicationsprotocol layer in response to failing to verify receipt of link layerdata packet receipt acknowledgements for all link layer data packetswithin the plurality of link layer data packets, a negative indicationof successful header compression control message transmission.

The program memory 612 further includes a header compression processorprogram 628 adapted to implement, subsequent to the link transportcommunications protocol to header compression layer interface providingthe indication, a header compression layer state change, and generate,in response to the header compression layer state change, a secondheader compression control message reflecting the header compressionlayer state change.

The communications processor 600 includes a data memory 610. Data memory610 stores data that support processing performed by CPU 602. The datamemory 610 of one embodiment of the present invention includes headercompressor context information 640. The header compressor contextinformation of one embodiment of the present invention includesconventional Robust Header Compression (RoHC) context information. Thedata memory 610 also includes header compression control message to linklayer data packet associations 642 and received link layer packetacknowledgements 644. As described above, the link transport layerprocessing associates with each header compression control message thelink layer packets conveying that message. The received link layerpacket acknowledgements are received, which are stored in the receivedlink layer packet acknowledgement 644, are used to determine if theheader compression control message was fully received, as is describedabove.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which—when loaded in a computersystem—is able to carry out these methods. Computer program means orcomputer program in the present context mean any expression, in anylanguage, code or notation, of a set of instructions intended to cause asystem having an information processing capability to perform aparticular function either directly after either or both of thefollowing a) conversion to another language, code or, notation; and b)reproduction in a different material form.

Each computer system may include, inter alia, one or more computers andat least one computer readable medium that allows the computer to readdata, instructions, messages or message packets, and other computerreadable information. The computer readable medium may includenon-volatile memory, such as ROM, Flash memory, Disk drive memory,CD-ROM, SIM card, and other permanent storage. Additionally, a computermedium may include, for example, volatile storage such as RAM, buffers,cache memory, and network circuits.

The terms program, software application, and the like as used herein,are defined as a sequence of instructions designed for execution on acomputer system. A program, computer program, or software applicationmay include a subroutine, a function, a procedure, an object method, anobject implementation, an executable application, an applet, a servlet,a source code, an object code, a shared library/dynamic load libraryand/or other sequence of instructions designed for execution on acomputer system.

Reference throughout the specification to “one embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment of thepresent invention. Thus, the appearances of the phrases “in oneembodiment” in various places throughout the specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments. Moreover theseembodiments are only examples of the many advantageous uses of theinnovative teachings herein. In general, statements made in thespecification of the present application do not necessarily limit any ofthe various claimed inventions. Moreover, some statements may apply tosome inventive features but not to others. In general, unless otherwiseindicated, singular elements may be in the plural and visa versa with noloss of generality.

While the various embodiments of the invention have been illustrated anddescribed, it will be clear that the invention is not so limited.Numerous modifications, changes, variations, substitutions andequivalents will occur to those skilled in the art without departingfrom the spirit and scope of the present invention as defined by theappended claims.

What is claimed is:
 1. A method for communicating header compressionlayer control messages, the method comprising: sending, by a linktransport communications protocol layer to a remote receiver, at leastone link layer data packet conveying a header compression controlmessage received from a header compression layer; receiving, at the linktransport communications protocol layer, link layer data packet receiptacknowledgements from the link transport communications protocol layerof the remote receiver for the at least one link layer data packet;determining, at the link transport communications protocol layer,successful transmission of the header compression control message basedon receiving, at the link transport communications protocol layer, thelink layer data packet receipt acknowledgements; providing, by the linktransport communications protocol layer to the header compression layer,an indication of successful header compression control messagetransmission, wherein the indication is based on the determining, at thelink transport communications protocol layer, successful transmission ofthe header compression control message; and changing, at the headercompression layer, a state of a header compression processor only inresponse to receiving the indication of successful header compressioncontrol message transmission from the link layer data packet receiptacknowledgments.
 2. The method of claim 1, wherein the headercompression control message comprises at least one of a headercompression context message, a Robust Header Compression Protocol IRmessage, a Robust Header Compression Protocol IR-DYN message, a RobustHeader Compression Protocol Packet Type 2 message, a Robust HeaderCompression Protocol UOR-2 message, a Robust Header Compression ProtocolUOR-2-ID message, a Robust Header Compression Protocol UOR-2-TS message,and a Robust Header Compression Protocol R-0-CRC message.
 3. The methodof claim 1, wherein the link transport communications protocol layerimplements one of an automatic repeat request protocol and a hybridautomatic repeat-request protocol.
 4. The method of claim 1, wherein theheader compression layer implements a Window-based Least Significant Bitheader compression algorithm, and wherein the header compression controlmessage comprises one of a Robust Header Compression Protocol IRmessage, a Robust Header Compression Protocol IR-DYN message, a RobustHeader Compression Protocol Packet Type 2 message, and a Robust HeaderCompression Protocol UOR-2 message, the method further comprising:implementing, subsequently to the providing, a header compression layerstate change; generating, by the header compression layer in response tothe header compression layer state change, a second header compressioncontrol message reflecting the header compression layer state change;sending, by the link transport communications protocol layer to theremote receiver, a second at least one link layer data packet conveyingto the second header compression control message; receiving, at the linktransport communications protocol layer, link layer data packet receiptacknowledgements from the link transport communications protocol layerof the remote receiver for the second at least one link layer datapacket; determining, at the link transport communications protocollayer, successful transmission of the second header compression controlmessage based on receiving the link layer data packet receiptacknowledgements for the second at least one link layer data packet; andproviding, to the header compression layer, an indication of successfulsecond header compression control message transmission, wherein theindication is based on the determining, at the link transportcommunications protocol layer, successful transmission of the secondheader compression control message.
 5. The method of claim 1, furthercomprising: dividing the header compression control message into aplurality of link layer data packets; associating each link layer datapacket within the plurality of link layer data packets with the headercompression control message; and wherein the receiving comprisesverifying receipt of link layer data packet receipt acknowledgementsfrom the remote receiver for each link layer data packet within theplurality of link layer data packets, wherein the providing comprises:providing, from the link transport communications protocol layer inresponse to verifying receipt of link layer data packet receiptacknowledgements for all link layer data packets within the plurality oflink layer data packets, a positive indication of successful headercompression control message transmission; and providing, from the linktransport communications protocol layer in response to failing to verifyreceipt of link layer data packet receipt acknowledgements for all linklayer data packets within the plurality of link layer data packets, anegative indication of successful header compression control messagetransmission.
 6. A header compression layer control messagecommunications system, comprising: a link transport communicationsprotocol transmitter adapted to send to a remote receiver, according toa link transport communications protocol layer, at least one link layerdata packet conveying a header compression control message received froma header compression layer; a link transport communications protocolacknowledgement receiver adapted to receive, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements from a link transport communications protocol layer ofthe remote receiver for the at least one link layer data packet; aheader compression control message transmission monitor adapted todetermine, at the link transport communications protocol layer,successful transmission of the header compression control message basedon receiving, at the link transport communications protocol layer, thelink layer data packet receipt acknowledgements; a link transportcommunications protocol to header compression layer interface adapted toprovide, to the header compression layer, an indication of successfulheader compression control message transmission, wherein the indicationis based on the header compression control message transmission monitordetermining, at the link transport communications protocol layer,successful transmission of the header compression control message; theheader compression layer further adapted to change a state of a headercompression processor only in response to receiving the indication ofsuccessful header compression control message transmission from the linklayer data packet receipt acknowledgments.
 7. The header compressionlayer control message communications system of claim 6, wherein theheader compression control message comprises at least one of a headercompression context message, a Robust Header Compression Protocol IRmessage, a Robust Header Compression Protocol IR-DYN message, a RobustHeader Compression Protocol Packet Type 2 message, a Robust HeaderCompression Protocol UOR-2 message, a Robust Header Compression ProtocolUOR-2-ID message, a Robust Header Compression Protocol UOR-2-TS message,and a Robust Header Compression Protocol R-0-CRC message.
 8. The headercompression layer control message communications system of claim 6,wherein the link transport communications protocol layer implements oneof an automatic repeat request protocol and a hybrid automaticrepeat-request protocol.
 9. The header compression layer control messagecommunications system of claim 6, wherein the header compression layerimplements a Window-based Least Significant Bit header compressionalgorithm, and wherein the header compression control message comprisesone of a Robust Header Compression Protocol IR message, a Robust HeaderCompression Protocol IR-DYN message, a Robust Header CompressionProtocol Packet Type 2 message, and a Robust Header Compression ProtocolUOR-2 message, the header compression layer control messagecommunications system further comprising: a header compression processoradapted to implement, subsequent to the link transport communicationsprotocol to header compression layer interface providing the indication,a header compression layer state change, and generate, in response tothe header compression layer state change, a second header compressioncontrol message reflecting the header compression layer state change,wherein the link transport communications protocol transmitter isfurther adapted to send to the remote receiver, according to a linktransport communications protocol layer, a second at least one linklayer data packet conveying to the second header compression controlmessage; wherein the header compression control message transmissionmonitor is further adapted to receive, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements from the link transport communications protocol layerof the remote receiver for the second at least one link layer datapacket; and the link transport communications protocol to headercompression layer interface further adapted to provide, to the headercompression layer, an indication of successful second header compressioncontrol message transmission based on the header compression controlmessage transmission monitor receiving, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements for the second at least one link layer data packet. 10.The header compression layer control message communications system ofclaim 6, wherein the link transport communications protocol transmitteris further adapted to: divide the header compression control messageinto a plurality of link layer data packets; associate each link layerdata packet within the plurality of link layer data packets with theheader compression control message, wherein the link transportcommunications protocol acknowledgement receiver is adapted to receiveby verifying receipt of link layer data packet receipt acknowledgementsfrom the remote receiver for each link layer data packet within theplurality of link layer data packets, and wherein the link transportcommunications protocol to header compression layer interface adaptedto: provide, from the link transport communications protocol layer inresponse to verifying receipt of link layer data packet receiptacknowledgements for all link layer data packets within the plurality oflink layer data packets, a positive indication of successful headercompression control message transmission; and provide, from the linktransport communications protocol layer in response to failing to verifyreceipt of link layer data packet receipt acknowledgements for all linklayer data packets within the plurality of link layer data packets, anegative indication of successful header compression control messagetransmission.
 11. A header compression layer control messagecommunications system, comprising: a physical communications layeradapted to couple to a physical communications medium; a link transportcommunications protocol transmitter adapted to send through the physicalcommunications layer to a remote receiver, according to a link transportcommunications protocol layer, at least one link layer data packetconveying a header compression control message received from a headercompression layer; a link transport communications protocolacknowledgement receiver adapted to receive, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements through the physical layer from a link transportcommunications protocol layer of the remote receiver for the at leastone link layer data packet; a header compression control messagetransmission monitor adapted to determine, at the link transportcommunications protocol layer, successful transmission of the headercompression control message based on receiving, at the link transportcommunications protocol layer, link layer data packet receiptacknowledgements; a link transport communications protocol to headercompression layer interface adapted to provide, to the headercompression layer, an indication of successful header compressioncontrol message transmission, wherein the indication is based ondetermining, at the link transport communications protocol layer,successful transmission of the header compression control message; andthe header compression layer further adapted to change a state of aheader compression processor only in response to receiving theindication of successful header compression control message transmissionfrom the link layer data packet receipt acknowledgments.
 12. The headercompression layer control message communications system of claim 11,further comprising a data interface adapted to accepting data to betransmitted and providing data that has been received to a data sourceand processor.